Now we're moving onto issues with the pancreas! The pancreas, as you should recall, secretes a lot of digestive enzymes. To be more specific, it secretes the inactive precursors of digestive enzymes. I've italicised "inactive precursors" because that is crucial here: if they are activated in some way, they can wreak havoc (they are meant to chew things up, after all).
Pancreatitis, or infection of the pancreas, has several causes. It can be caused by gallstones, infection, excessive alcohol consumption, cystic fibrosis (which impairs secretion of digestive enzymes) and cancer. Complications of pancreatitis can include sepsis, perforation and peritonitis (inflammation of the peritoneum) if prematurely activated enzymes are running around digesting your pancreas.
Intestines
The intestines, as you should know, are where most absorption takes place. The important thing to note here is that the balance between secretion and absorption is pretty important: food and digestive juices are secreted into the intestine, and most of that is absorbed (and what isn't absorbed is shat out). Naturally it's pretty important to keep that balance, because if too much is secreted or too little is absorbed, you're gonna have a runny, unpleasant problem at the other end, to say the least. Additionally, if there are problems with absorption, then your body can't get the nutrients that it needs.
The intestines are also important as a barrier: they stop bad stuff from getting in. There are a bunch of immune cells in the mucosa, some organised into Peyer's patches, that help to protect us, but may also be responsible for food allergies.
Coeliac Disease
Coeliac disease is an example of an immune response going wrong. The offender here is gliadin, which is a protein found within gluten. Mutations in the HLA-DQ 2/8 alleles can lead to production of autoantibodies (i.e. antibodies that attack the self). In fact, diagnosis for coeliac disease involves looking for antibodies to gliadin, as well as to tTG (tissue transglutaminase) and EMA (endomysial antibodies).
These antibodies can wreak havoc in your gut, destroying the villi and their large surface area for absorption. This can lead to diarrhoea and pain in the short term, and over time anaemia and weight loss due to decreased absorption. Coeliac disease symptoms are not always the same from person to person, however, making it somewhat difficult to diagnose.
Gluten Sensitivity/Intolerance
Some people appear to get mild, non-specific symptoms upon exposure to gluten. However, this is not very well understood, particularly since most cases appear to be self-diagnosed.
Lactose Intolerance
Lactose intolerance results from a deficiency in the enzyme lactase. Lactase is deficient in most adults- Caucasians are unusual in that they tend to have more lactase than other ethnicities. When lactase fails to digest lactose, bacteria break it down instead, leading to nausea, cramps, bloating, gas and diarrhoea.
Food Allergies
Food allergies are allergies to food. Am I the new Captain Obvious now?
Allergic responses to food tend to be of the type I variety: IgE on mast cells recognises an antigen, the mast cells degranulate, and scary shit happens. Sometimes scary shit can turn into dangerous shit in the case of anaphylaxis. Thankfully, not all allergies are lifelong: many children outgrow allergies to eggs, milk, soy and wheat.
Infections
Bacteria and other pathogens that survive the highly acidic environment in the stomach can colonise the intestine. We have many micro-organisms in our intestines that live happily alongside us, but others can be pretty nasty.
Clostridium difficile (C. diff) is one example of a nasty little bugger. It can cause diarrhoea, sensitivity to light, and all other kinds of lovely symptoms. Interestingly enough they're looking at synthetic stool and/or poop transplants as a means of treating this guy.
EHEC (enterohaemorrhagic E. coli) is a nasty form of E. coli. While many forms of E. coli can live happily in our gut without any problems, EHEC (a.k.a. O157:H7) cannot. Thankfully, it's normally only resident in cow intestines, but when it gets into us, it can cause pain, bloody diarrhoea and vomiting. If the toxins escape, kidney damage and haemolysis can also result. This is especially bad in the young and the elderly.
Diarrhoea
Diarrhoea is a common response to infection, as it helps to get rid of the bad stuff. Diarrhoea, as I'm sure you're aware, is when there is an increased water content in the faeces. This can be due to increased water secretion or decreased absorption, as mentioned earlier in this post. Secretion may be increased due to infections such as cholera and C. diff. The increased fluid volume and some other signals increase gut motility, helping to get the germs out faster. This can be problematic if too much is lost within too short a time, however, as it can cause an electrolyte imbalance.
Appendicitis
I'm sure you're fairly well aware of appendicitis, but I'll talk about it anyway. If the appendix gets blocked, it can become inflamed, leading to further infection, inflammation, swelling and necrosis. This leads to pain in the lower right quadrant of the abdomen. If the appendix ruptures and forms an abscess, the omentum can stick over the abscess and seal it off, but if this isn't effective, peritonitis can occur.
And that's the end of that post! Sorry that it wasn't super well organised- as I've said before, these lectures were not particularly well organised.
No comments:
Post a Comment